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ARLINGTON (CBSDFW.COM) – Investigators believe a man who works for the Dallas County Sheriff’s Department is responsible for killing a pregnant woman.

Arlington police arrested Keith Haynes and charged him with the capital murder of Kenishia Walker and her unborn child.

An arrest affidavit reveals Walker’s friends believed the child she was carrying belonged to Haynes.

The document also shows Walker would send screenshots of her conversations with Haynes and told her friend at one point on March 30, “If I ever come up dead please show the police this and the other screenshots.”

The arrest warrant indicates the two knew each other since high school and that Haynes wanted to “rekindle” their relationship. The report shows Walker refused to get back together with Haynes because he had lied to her in the past.

The Dallas County Sheriff’s Department said Haynes employment is under review in light of the charges.

The department also indicated there is a pending internal affairs investigation over a 2016 incident where Haynes was accused of smuggling a cellphone to a family member inside a Mississippi prison.

Haynes is being held on a $250,000 bond.

He is expected to be transferred to the Tarrant County Jail.